Writing down and balancing the chemical equation for the reaction is the first step in figuring out how many grammes of H2 can be produced from 18.01 grammes of Al:
3 H2 + 2 AlCl3 = 2 Al + 6 HCl
The balanced equation reveals that two moles of aluminium react with three moles of hydrogen gas to create two moles of aluminium chloride. The mole ratio of Al to H2 is therefore 2:3.
We must convert 18.01 grammes of aluminum's mass to moles by using its molar mass in order to determine how many moles of H2 can be created from that amount of aluminium.
Al's molar mass is 26.98 g/mol.
Moles of Al are equal to 18.01 g / 26.98 g/mol, or 0.668 mol.
We can determine how many moles of H2 can be created using the mole ratio of Al to H2:
moles of H2 = (2/3) × 0.668 mol = 0.445 mol
Using its molar mass, we can finally translate the quantity of H2 in moles to grammes:
molar mass of H2 = 2.02 g/mol
grams of H2 = 0.445 mol × 2.02 g/mol = 0.898 g
As a result, 18.01 grammes of Al can be used to produce 0.898 grammes of H2.